The lymphatic system is often referred to as the body's "secondary circulatory system." The lymphatic system collects excess fluid in the body’s tissues and returns it to the bloodstream. Lymph formation occurs at the microscopic level. During the exchange of fluid and molecules between the blood circulation and body tissues, blood capillaries may not reabsorb all of the fluid. Surrounding lymphatic capillaries absorb the excess fluid. The fluid is then filtered and transported back by the lymphatic system into large veins near the heart. The lymphatic system can play a very worrisome role in the spread of breast cancer. Components of the lymphatic system called lymph nodes are distributed at specific locations throughout the body. There is also an extensive network of lymphatic vessels in every woman’s breast tissue, which is important in regulating the local fluid balance as well as in filtering out harmful substances.The lymph vessels in the breast may inadvertently supply cancerous cells with access to a highway along which the cancerous cells can move to other parts of the body. This process is called metastasis and may result in the formation of a secondary cancer mass in a different location of the body. Regular breast self examinations can help to detect tumors earlier in their growth, hopefully before they spread quickly or metastasize.
Breast Cancer cells migrate through the blood vessels or lymphatic channels. Breast cancer cells will typically travel wither through the lymphatic system or through blood vessels to reach distant areas of the body. When breast cancer metastasize to the axillary lymph nodes (under the arm) it is still considered to be a relatively early stage of metastasis, and is potentially curable. But once the breast cancer moves beyond the lymph nodes into other areas of the body, it is usually termed a ‘distant‘ metastasis, and a patient is unfortunately usually not curable at that point. Metastatic breast cancer is called ‘systemic’. If breast cancer has metastasized beyond the lymph nodes it is termed a ‘systemic‘ disease. That means that the ‘whole body‘ must be treated and not just a particular spot. The only way to effectively treat the whole body is through chemotherapy and hormonal therapy.
The lymphatic system is part of the circulatory system and a vital part of the immune system, comprising a network of lymphatic vessels that carry a clear fluid called lymph (from Latin, lympha meaning "water") directionally towards the heart. The lymphatic system was first described in the seventeenth century independently by Olaus Rudbeck and Thomas Bartholin. Unlike the cardiovascular system, the lymphatic system is not a closed system. The human circulatory system processes an average of 20 liters of blood per day through capillary filtration, which removes plasma while leaving the blood cells. Roughly 17 litres of the filtered plasma are reabsorbed directly into the blood vessels, while the remaining three litres remain in the interstitial fluid. One of the main functions of the lymph system is to provide an accessory return route to the blood for the surplus three litres.
The other main function is that of defense in the immune system. Lymph is very similar to blood plasma: it contains lymphocytes and other white blood cells. It also contains waste products and cellular debris together with bacteria and proteins. Associated organs composed of lymphoid tissue are the sites of lymphocyte production. Lymphocytes are concentrated in the lymph nodes. The spleen and the thymus are also lymphoid organs of the immune system. The tonsils are lymphoid organs that are also associated with the digestive system. Lymphoid tissues contain lymphocytes, and also contain other types of cells for support. The system also includes all the structures dedicated to the circulation and production of lymphocytes (the primary cellular component of lymph), which also includes the bone marrow, and the lymphoid tissue associated with the digestive system.
The blood does not come into direct contact with the parenchymal cells and tissues in the body (except in case of an injury causing rupture of one or more blood vessels), but constituents of the blood first exit the microvascular exchange blood vessels to become interstitial fluid, which comes into contact with the parenchymal cells of the body. Lymph is the fluid that is formed when interstitial fluid enters the initial lymphatic vessels of the lymphatic system. The lymph is then moved along the lymphatic vessel network by either intrinsic contractions of the lymphatic passages or by extrinsic compression of the lymphatic vessels via external tissue forces (e.g., the contractions of skeletal muscles), or by lymph hearts in some animals. The organization of lymph nodes and drainage follows the organization of the body into external and internal regions; therefore,